No, they aren't outdated. I don't know if they're still taught in school, but they're very practical in writing. In addition, they're not indicated in dictionaries as archaic or obsolete.
If somebody said to me, "Wow, you must be OLD if you use things like that," I'd let my eyes get big and respond, "Really?..." as I look the person in the face.
Of course, you don't want to express yourself in a snooty way - but any seeming snootiness would not be caused by the use of "i.e." or "NB."
Don't let people make you feel inferior just because you may write like an educated person.